


Crash Course in Omegas

by Cryo_Bucky



Series: ABO Stucky Prompts [4]
Category: Captain America (Movies)
Genre: Alpha Bucky Barnes, Alpha/Beta/Omega Dynamics, M/M, Mating Cycles/In Heat, Omega Steve Rogers, Pre-Captain America: The First Avenger, Pre-Serum Steve Rogers
Language: English
Status: Completed
Published: 2016-10-14
Updated: 2016-10-14
Packaged: 2018-08-22 07:46:30
Rating: Explicit
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 1
Words: 4,241
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/8278250
Author URL: https://archiveofourown.org/users/Cryo_Bucky/pseuds/Cryo_Bucky
Summary: One of the prompts written for ohmyomegasteveandalphabucky on tumblr!Bucky knows he's an alpha, but when he comes home and Steve goes into heat it's time for a crash course in Omega physiology.





	

Steve is _tiny._ That’s the first thing that everyone seems to notice about him. Whenever they look at him they see a spindly guy with bad lungs. The next thing they notice is that Steve is 95 pounds of snark and vinegar stuffed into his five-foot frame. 

Bucky had noticed the latter first, mostly because he’d pulled Steve out of a dumpster after the kid had been thrown in there for standing up to Jason Costalano and his band of dickish friends. Not long after that Bucky had made a full-time job of breaking up fights that involved Steve. He loved the kid to death but sometimes he wanted to be able to walk down the street and not look down an alley and see his best friend being beaten to a pulp. 

The other notable thing about Steve was he’s almost always sick. Bucky wasn’t sure if it was by proxy of being so little, or if being little was somehow a byproduct of being sickly. Watching Steve struggle through every winter with pneumonia was hard enough, it wasn’t his fault that he missed out on so much being sick so often, and Bucky purposefully ignored his protests when Steve tried to get him to go out with his other friends. 

Bucky didn’t need other friends anyway. 

No one was surprised when Bucky presented as alpha at 15, and everyone seemed even less astounded when Steve didn’t present as anything at all. 

A few years later when Steve’s mom passed and Bucky had to force Steve to move in with him people still barely raised an eyebrow. They’d been SteveandBucky since they’d met in school, and no one questioned them anymore. 

Bucky wasn’t ashamed of his nature, but he pointedly avoided putting any of his weird Alpha stuff onto Steve. Steve was a Beta, and the last thing he needed to hear about was Bucky pining for a mate during his ruts. 

“Stevie, I’m home!” Bucky pushed the front door open, toeing off his shoes and running his fingers through his hair to free it from the pomade. 

“Hey Buck.” Steve wandered out of their room, looking tired and flushed. 

Bucky sighed, worry immediately creeping up on him, “You still up for our double date later?” He knew better than to ask how Steve was feeling, that’d just get him a smart answer and probably lead to a fight. 

Steve slumped a bit, looking work down. “I dunno… I feel like a real jerk skipping out, but I don’t feel so great. Think I’ve got another fever.”

Bucky crossed the room, reaching out to gently touch Steve’s shoulder. “I understand. We can just re-schedule. It’s no big deal.” 

Steve looked up at him. “No way. You know that these dames are never really interested in me anyway.” 

Bucky jostled him. “Don’t be so hard on yourself punk, I’ll find someone good enough for you.” 

Steve huffed. “I really don’t need your help Buck.” 

Bucky opened his mouth to argue and was immediately assaulted by an intoxicatingly sweet scent. Oh God, what was that? 

Steve swayed next to him, gripping the edge of the counter and swearing under his breath. 

“Steve-” Bucky took another deep breath and he felt his knees go to jello. Oh fuck, that was heat scent. What was going on? 

A high whine was the only reply he got from his friend. 

“Steve I don’t-” Bucky moved to reach out for him, but another wave of heat scent washed over him and he stumbled back.  
Steve released his death grip on the counter and immediately pressed up against Bucky, his eyes unfocused as another whine crawled from his throat. “Alpha…”  
No way, Steve was Omega? Could he even present this late? Bucky scrambled away from him, ignoring his instincts screaming for him to go and comfort the hurting Omega. 

Steve wobbled again, dropping heavily into one of their kitchen chairs pressing his cheek against the smooth wood of the table. “So hot…” His words were a little slurred. “Probably have the fever again…” 

Bucky backed across the room so fast he nearly tripped over his own feet, the enticing smell making his head swim. Fuck, this was so bad. 

Steve had managed to pull his head off the table, his eyes a bit unfocused. “What? C’mon Buck, it’s not like I have the plague or somethin’. You’re freaking me out.” Steve seemed to have regained himself a little once Bucky backed off. 

Bucky made a small choked noise in the back of his throat. “Steve, I think you’re going into heat…” 

Steve just blinked at him, confusion written on his face. “What do you mean?” 

Bucky made another embarrassing noise, pressing himself back against the wall. “Well it seems like you’re a late bloomer, pal, because if there’s one thing I know it’s the smell of an Omega in heat. Trust me.”

Steve wiggled in his seat and Bucky almost toppled over as the enticing scent slowly filled the room. He felt like someone had shrunk his skin and he was going to burst.

“Listen Steve…” Bucky managed to pull himself together for a moment. Steve had spent almost all of middle school in bed, and had therefore missed out on the basic nature section of their health class. No one had ever worried about him, since it had seemed clear that he was a Beta, it didn’t affect him anyway. But now, if Steve was an Omega he needed a serious crash course. 

Bucky nearly screamed when he felt a light touch on his arm, looking down into his best friend’s wide blue eyes. When had Steve even moved? 

“Buck…” Steve was rubbing up against him again, his pupils already blown out as the alluring scent leaked from his pores. 

Bucky pushed him away, feeling like a total heel at the pained sound he got in response. “Stay away from me Steve, I mean it. Shit, this is so bad.”

Steve was frozen in place, looking needy and hurt and confused all at once. 

“I know this isn’t the best time but I guess we gotta do the crash course here.” Bucky ran his hands through his hair again, sure that that the strands were sticking up like crazy now. “If you’re going into heat then you’re presenting as an Omega. I didn’t know you could present this late, but that doesn’t really matter now.”

Steve was staring at him, his gaze a little more focused but still plaintive. If there was something Bucky thought he’d never see it was Steve’s bedroom eyes. 

“You’re really vulnerable during your heat, and we should probably get you on suppressants. Every alpha in a mile radius is gonna be sniffin’ around now smelling how sweet you are. Honestly I should probably go, being unmated and all it’s-” Bucky was babbling a bit, but anything at all to keep him from focusing on just how enticing Steve smelled was a plus at this point. “It’s a pretty shit situation. There’s not really a lot we can do now that it’s started. I mean I don’t know a whole lot about heats, but my ruts can be pretty intense, and I assume it’s along the same lines.” Bucky felt his ears burn at the thought of just what it was like. “So, uh, I mean there’s not a lot I can do besides stay away from you while it dies down…”

Steve wobbled again. “I feel dizzy…” 

Bucky raced over to him before Steve could crumple to the floor. Damn, the heat was hitting him hard, though Steve’s weak constitution didn’t leave it much of a surprise. 

As soon as Bucky touched him Steve was all over him, twisting in his grip and pressing against him as much as possible, rubbing the sweetness of his heat scent all over him. 

Bucky was drowning, there was no way he was going to be able to resist this. He’d never been able to deny Steve anything. But there was no way that he was going to force himself onto his friend. Just because Steve was in heat didn’t mean he wasn’t still Steve and didn’t still deserve to be treated with respect. There was no way Bucky was going to be like that. 

With Steve distracted rubbing against him Bucky was able to dump him on the bed and slam the bedroom door behind him before Steve had recovered. Shoving one of the kitchen chairs under the knob kept it closed and Bucky leaned heavily on the edge of the couch, trying to steady himself. This was the worst. 

Steve banged on the door for a few moments before realizing that he couldn’t open it and just leaned heavily against it. Bucky tried to ignore the pull he felt deep in his core. 

“If you’re in heat then your body’s gonna be looking for a suitable Alpha t’ mate with ya. Your body wants to, uh, breed.” It felt so dirty saying it, but he wasn’t going to lie. Heats were for breeding, there was no two ways about it. 

Bucky couldn’t convince himself to actually leave Steve in their apartment alone. He didn’t trust that he would be safe, or that’s what he kept telling himself. The scent was a bit more muted behind the door but now he had to listen to plaintive whimpers and the occasional squeak of bedsprings as Steve paced and tried calm himself down. The last thing he needed to think about was Steve spread out on the bed, flushed red all the way down his chest and… 

“Fuck, fuck, fuck.” Bucky considered banging his head against the wall, anything as long as it distracted him from his throbbing hard-on. If he thought beating off would help he would happily do it, but there was no way that he would be able to relax with Steve… like that.

What was wrong with him? He should be able to handle this. This was Steve. Just because he was an Omega didn’t change anything between them. Maybe he’d had a few impure thoughts, but that didn’t mean anything, right? He refused to project his own desires onto his friend, especially when he was in an extremely compromised state. 

A soft knock on the door startled Bucky out of his reverie. “What is it Steve?” His voice was a little hoarse, and he swallowed thickly, trying to get himself under control. 

“Let me out Bucky.” Steve sounded very convincingly normal, and Bucky wanted to listen. “This is ridiculous.”

“Sorry, can’t do that pal. The last thing we need is to go losing our heads here.” Honestly that was mostly directed toward himself. “I won’t let some dumb Alpha put their hands on you.” 

“You’re not some dumb Alpha.” Steve’s voice was muffled, like he was pressed up against the door and trying to lure Bucky through the woodgrain. Which was probably exactly what he was doing. 

“C’mon Steve, don’t let your heat talk for you. You don’t want me like that.” Was he trying to convince himself or Steve?

“Please Buck? I’ll be good for you, I promise.” The needy whine was back in Steve’s voice and Bucky felt his heart skip. 

Bucky smoothed his hands over his face, licking his lips absently and trying to distract himself from the literal tidal wave of filth his mind was supplying him with. 

“At least help me out a little you big jerk.”

Now that sounded like Steve. 

“I’m not coming in there.” Bucky felt himself gravitating toward the bedroom door, grabbing the other chair to plant himself in front of it. “You’re just gonna have to entertain yourself.”

There was a long pause. “What good’s that supposed to do?” 

Bucky ground his teeth together, trying to resist the urge to throw himself out the window. “It’ll take the edge off, I dunno. It’s what I do during my rut. You’ve touched yourself before.” 

“Of course I have. I’m not a child. I just meant… I dunno, it feels different now. God, Buck, I’m so wet…” 

Bucky was pretty sure his brain was going to short itself out. Surely on his tombstone it would read “dead by Steven Rogers’s mouth”. 

“Like I said, touch yourself Stevie.” Bucky’s voice was low and thick, like he was drunk. He felt a bit drunk. 

A harsh moan cut through the air and Bucky couldn’t fight back a growl in response. 

“C’mon Stevie, you know what you need.” Bucky had no idea what possessed him to babble on, but he couldn’t bite it back, he was just so horny. “Gotta put something in your needy hole.” It couldn’t hurt to guide Steve through it, right? It wasn’t like Bucky had kept secrets about what he did in bed with dames; Steve knew he had a foul mouth.

The soft thump of Steve leaning against the door reached Bucky’s ears just before the quick shuffling of clothes and a bitten-off moan. 

“Start with a finger or two.” The words fell from his mouth unbidden. Fuck, the last thing that Bucky needed was to add to his fantasies. “Stretch yourself open.” 

“Yes Alpha.” 

The words punched all the air out of Bucky’s lungs and he growled again, his eyes fluttering closed and his hand going to his fly. If Steve was gonna get off what was the harm in him doing it too?

Even through the door Bucky could smell the sweetness of Steve’s heat, and it was driving him crazy. He’d smelled heat before, lingering on someone’s skin as they walked past him on the street, but to have the full force in his face and directed toward him left him dizzy with desire. 

“S’not enough…” Steve whimpered. “Want your knot, please Bucky?” 

Bucky groaned aloud, shoving his hand down his pants like a horny kid. “Fuck, Steve, you know I can’t…” 

“Please? I’ll be so good for you. You don’t gotta be my mate or nothin’, just want you to touch me a little. I promise I’ll be good for you.” 

Bucky cursed himself, knowing he was weak as he curled his hand around the leg of the chair against the door. 

“I wanna feel your knot.” Steve whimpered like he was ashamed. “Want you to split me open with it…” 

Bucky had wrenched the door open before he realized what he was doing, the full force of Steve’s heat hitting him hard enough to make him sway in place. Was this what it was like for everyone? Or maybe it was just because it was Steve, and they were so wrapped up in each other that this was just how it was going to be. Bucky wanted Steve as his mate, had thought about it since before he’d even presented, but relationships between non-standard pairings were looked down on and he’d pushed it aside. If Steve was an Omega then he could really have what he wanted. 

Steve sprawled across the floor when Bucky yanked the door open, his eyes blown so wide there was only a tiny ring of blue left. Bucky leaned down and heaved him up by the arm, crushing him against his chest and burying his nose in his neck. God, he smelled so sweet, like spun sugar and sex, but still like Steve. That was the best part really, and Bucky knew it.

Steve plucked at his shirt, the delirium of his heat coming and going at random. “Buck, please? I know I’m not the best but-”

Bucky growled again, in anger this time. How dare Steve talk about himself that way. They both knew he was better than that. He was the best of them, he was gonna go somewhere and do big things with his life, and everyone was gonna see how great he was just like Bucky did every day. “That’s my line, punk.” 

Steve blinked at him, gone all shivery and soft again. “Wanna be good for you…” 

Dammit, did everything out of Steve’s mouth have to be so sincere? Bucky crushed their lips together without a second thought, moaning at just how sweet Steve’s mouth was. It was messy and their teeth clacked together, but it was still the best kiss of Bucky’s life. Steve kissed like he did everything else, all or nothing, and it left Bucky shaking. Steve wrapped his legs around Bucky’s hips and rubbed languidly against him as they kissed. 

Once they’d pulled apart Bucky realized that there was a growing damp spot on his pants. Fuck, Steve was leaking like a faucet, the sugary scent of his arousal adding to the heat scent that he was dousing Bucky with. 

Bucky let him down, ignoring Steve’s whine of protest. “You wanna be my good little Omega?” The syrupy quality of his voice had returned full-force and Steve swayed a little under it. “Get on the bed, clothes off.”

Bucky couldn’t shake the thought that maybe this was a bad idea. What if Steve decided he didn’t want him? Watching Steve scramble onto the bed and sprawl out, his eyes wide and trusting and undeniably still himself soothed Bucky a bit. Steve might have been out of it with his heat, but to say that he was a drooling invalid because of it was a lie. Omegas could still control themselves, no matter what the media tried to push. If Steve said he wanted him then he really did, heat or no heat. 

Bucky stalked over to the bed, licking his lips again and crawling onto the mattress. Steve squirmed under his gaze, immediately reaching out to pull him into another kiss.

“I still don’t really know what’s goin’ on here Buck…” Steve mumbled against his lips. “But God, you smell so good, I just want your hands on me.” 

Bucky chuckled, rolling their hips together. “Well you’ve got me now Stevie.” Bucky ran his fingers down Steve’s legs, both of them gasping as his finger circled Steve’s fluttering hole. 

“Buck-”

Bucky dug his fingers into Steve’s hip. “What do you call me?” 

Steve went shivery again, arching his back as Bucky thumbed at his hole. “Alpha…” 

Bucky gave him another kiss in reward, sucking his fingers into his mouth to lick off the sweet slick. God, Steve tasted so good. Pressing gentle kisses across Steve’s shoudlers and down his chest Bucky continued to pet his thighs, loving the way 

Steve trembled. “Turn over for me.” 

Steve immediately rolled onto his belly, arching his back and trying his best to present like a good little Omega. Bucky felt his cock throb. 

“Look at you, pretty little thing.” Bucky smoothed his hands down Steve’s back, sucking a mark into his shoulder. “Gonna feel so good caught on my knot.”

Steve gasped, his hips twitching and Bucky watched more slick leak from him. Fuck, that was so hot. 

“You’re makin’ a real mess of yourself, Stevie.” Bucky kissed his way down the nobs of Steve’s spine before kissing his thigh. “Bet you taste as good as you smell.” 

“Oh please…” Steve arched his back higher, his hole winking under Bucky’s scrutiny.  
It didn’t take any more prompting for Bucky to bury his face between Steve’s thighs, licking up the sweet slick like toffee sugar. 

Steve howled when Bucky mouthed at him, and Bucky shoved two fingers into his mouth to lower the decibels. Their neighbors didn’t need to hear every second of this. 

Bucky lost himself for a few long moments, completely focused on chasing every drop of that sweet slick back to its source. It wasn’t until Steve’s cries went sharp he realized that just this was going to be enough to push him over.

Bucky immediately crawled up his body, one hand closing around Steve’s jaw to hold him in place as he shoved two fingers into his puffy hole. “You gonna come for me Omega?” Bucky snarled, sucking another mark into Steve’s throat. 

“Fuck, alpha, fuck-” Steve had dissolved into a real mess, shaking and drooling a bit from the onslaught of sensation. 

“Come.” Bucky put a bit of his Voice into the word, turning in into an order. It was more than enough to push Steve over the edge, his eyes rolling back and his voice breaking as he writhed his way through his orgasm.  
Not giving him any time to recover Bucky flipped them over again, curling against the headboard with Steve on his lap. 

“Want you to ride me Stevie…” Bucky pulled him into another filthy kiss, his fingers continuing to stretch Steve out to make room for his cock. Slick had started to drip down his hand. 

Once Steve had stopped shaking his way through his orgasm he was more than willing to let Bucky manhandle him, arching his back again and reaching to curl his long fingers around Bucky’s dick. “Please, I’m ready. So ready…” 

Bucky pulled his hand back, steadying Steve’s shoulders as he lined himself up and started to sink down. 

As much as Steve had insisted he was ready it was still slow going. Tight was the understatement of the century, and Bucky had to grip onto the headboard behind him to stop himself from thrusting up into the intensity of the feeling and let Steve sink down at his own pace. They were both panting by the time he bottomed out, Bucky’s knot already chubbing up at the base. 

“Oh God, Stevie…” Bucky’s eyes fluttered as he moved, very slowly pulling himself up and sinking back down. They both gasped. Sex had never been this intense before, it felt like Bucky was going explode. 

Steve was bouncing on his lap in earnest now, bracing his hands on the headboard and taking it like he was made for it. He looked so beautiful, flushed in a healthy way instead of sick with a fever, but his breaths were starting to wheeze a bit, and Bucky began to worry that he’d asked too much. 

“Steve…” Bucky cursed as Steve tightened around him. 

“Don’t you dare try to tell me to stop Barnes. I’ll kill you.” 

There he was, even through the heat he was still the same punk, and there was no way Bucky was going to tell him to stop. Shifting his position Bucky got his hands under Steve’s thighs, tipping them backwards and bending the smaller man nearly in half. 

Steve gasped and cursed like he was dying, pleading with renewed vigor as Bucky pushed inside him again. Apparently this angle was much better. 

Situating Steve’s legs over his shoulders Bucky hissed as the Omega’s blunt nails dug into his shoulders. 

“Fuck me Alpha, I can take it. Want it... want your knot.” 

Bucky was so done for, snapping his hips forward and snarling against Steve’s skin as he tried his hardest to fuck him through the bed. He knew he wasn’t going to last very long, but Steve didn’t seem to mind, his cries already going sharp and needy as his nails dug into Bucky’s back. 

It hardly took any time at all for Bucky’s knot to start to catch, popping obscenely on every thrust as Steve fluttered and tried to clamp down on him. 

“Fuck Steve, m’close…” Bucky could feel the urge to hold Steve down and bite swelling in his chest. He wanted to claim this beautiful omega as his so that no one would ever look sideways at him again, but there was no way that he was going to. Maybe once they had clear heads and could discuss it on equal terms, but in the throes of heat was not the best time. That didn’t stop Bucky from wanting it so bad his teeth itched.

“Oh Alpha, Bucky, please knot me, please, pleasepleaseplease, I want it-” Steve was babbling, trying to throw himself back into each thrust. 

Bucky shoved forward one last time, snarling his way through a filthy grind of his hips and tying them together, sinking his teeth into his lip to stave off the urge to bite as he finished

“O-oh, _oh._ ” Steve’s eyes rolled back as he came again, slick trying valiantly to bubble out around Bucky’s knot as he ground their hips together. 

And oh, Bucky was just gone. He’d never had this before, tying an Omega in heat was fundamentally different than just fooling around, every part of his biology doing its best to fill Steve up as much as possible, make him good and full and bred, and it kept Bucky’s orgasm going for long enough that he started getting black spots around the edges of his vision and left both of them twitching every time Steve squeezed around his knot.  
After a few long moments Bucky tipped them over, letting Steve’s legs down and twisting them both enough for Steve to spoon against him, ignoring Steve’s whines of protest every time he jostled him. Burying his nose in Steve’s hair Bucky tried to catch his breath, reaching blindly for the blanket and tugging it over them.

“That was great.” Steve mumbled, trying to press himself closer. 

Bucky couldn’t help but chuckle. “I try.”

Steve raised his arm to smack him but gave up halfway. “Jerk.” 

“You think you’re gonna survive your first heat?” 

Steve sighed. “Maybe now that my best guy has pulled his head out of his ass. Can you tell me more about being an Omega?”

Bucky grinned against Steve’s soft hair. “Sure, anything for you Stevie.”


End file.
